Debt (Non-Recourse Debt) (Details) $ in Millions	Sep. 30, 2025 USD ($) numberOfAgreement	May 21, 2025 USD ($)	Dec. 31, 2024 USD ($)
Debt Instrument [Line Items]
Number of warehouse facility agreements | numberOfAgreement	3
Auto loans receivable	$ 2,020.0		$ 1,103.8
Variable Interest Entity, Primary Beneficiary | Asset Pledged as Collateral
Debt Instrument [Line Items]
Restricted cash of consolidated VIEs	26.8		3.4
Auto loans receivable	609.7		24.5
Nonrecourse
Debt Instrument [Line Items]
Non-recourse debt	1,744.1		826.2
Less: unamortized debt discounts and debt issuance costs	(3.1)		(0.2)
Less: current maturities	(57.4)		(28.3)
Non-recourse debt, net of current maturities	1,683.6		797.7
Nonrecourse | Warehouse facilities
Debt Instrument [Line Items]
Aggregate capacity	1,400.0
Unused capacity	264.1
Remaining borrowing capacity	1.0
Nonrecourse | Warehouse facilities | Line of Credit
Debt Instrument [Line Items]
Non-recourse debt	$ 1,135.9		$ 801.5
Weighted-average annual interest rate	5.10%		5.40%
Nonrecourse | Warehouse Facility, August 2026 expiration
Debt Instrument [Line Items]
Aggregate capacity	$ 400.0
Nonrecourse | Warehouse facility, October 2026 expiration
Debt Instrument [Line Items]
Aggregate capacity	300.0
Nonrecourse | Warehouse Facility, May 2026 expiration
Debt Instrument [Line Items]
Aggregate capacity	700.0
Nonrecourse | Term securitization debt | Variable Interest Entity, Primary Beneficiary | Notes Payable, Other Payables
Debt Instrument [Line Items]
Non-recourse debt	608.2		$ 24.7
Nonrecourse | ANF Auto Receivables Trust 2025-1 [Member] | Variable Interest Entity, Primary Beneficiary | Notes Payable, Other Payables
Debt Instrument [Line Items]
Non-recourse debt	$ 608.2
Initial principal amount		$ 700.0
Nonrecourse | ANF Auto Receivables Trust 2025-1 [Member] | Variable Interest Entity, Primary Beneficiary | Minimum | Notes Payable, Other Payables
Debt Instrument [Line Items]
Percentage interest	4.72%
Nonrecourse | ANF Auto Receivables Trust 2025-1 [Member] | Variable Interest Entity, Primary Beneficiary | Maximum | Notes Payable, Other Payables
Debt Instrument [Line Items]
Percentage interest	5.63%